I know that the graph does some sort of smoothing on the data which might be causing the unexpected results in the actual visual graph, but I didn’t think that this carried over to the actual chart data .csv report. Have you tried downloading a larger set of historical data via the steps in this post to see if they match with the .csv that you’ve attached here?
Tagging @bestes for the feedback that most users I’ve encountered don’t want any smoothing done to their graph data.